Selling your idea to an existing company means selling your right to profit off your invention, so if you want to manufacture and sell your invention yourself and keep the profits, you'll need to start by making sure you have a legal "paper trail" that documents that this is your brainchild.

Even before you patent, documenting that your invention is strictly your own is an essential prerequisite. Speak with a patent attorney before you make any final decisions, but before, while, and after you do, keep documenting.

At the end of the day, even a patent isn't a fix-all--it's always up to you to defend your intellectual property rights in court.